Photographic materials containing filter dyes



Nov. 5, 1968 E. BCKLY ETAL 3,409,433

PHOTOGRAPHIC MATERIALS CONTAINING FILTER DYES Filed June 24. .1964

United States Patent O ABSTRACT OF THE DISCLOSURE Resolution and contrast of multicolor photographic images is improved when the images are made on threelayer combination of emulsions in which 'blue-sensitive emulsion is behind red-sensitive and green-sensitive emulsions, and both of the latter two emulsions or only thel green-sensitive one contains sulfonated .alkoxyphenylazoacylaminonaphthol dye as explained below, that sharply absorbs green and rinses out completely during processing.

The present invention relates to silver halide emulsions and to multilayer materials for color photography, which emulsions and materials contain dyestuffs that increase the sharpness of color images.

Multilayer materials for color photography, more especially printing materials, must meet high standards of sharpness and resolution and of color reproduction. It is known that these properties can be impaired by the scattering effect of the silver halide grains present in the layers.

This disadvantage is reduced in multilayer materials that have an interchanged layer arrangement and no yellow filter, such as described in German Patent 974,792. These .are multilayer materials in which the blue-sensitive silver halide layer is closest to the support, the greensensitive and the red-sensitive layers have va substantially lower blue sensitivity than the blue-sensitive layer and the silver halide layers contain color couplers for producing color images complementary to the sensitivities of the layers.

Furthermore, it is known that the light-sensitive layers of these multilayer materials can contain dyes which absorb in the spectral sensitivity region of the emulsions and which can be removed again .after the exposure. In the layers colored in this way, the harmful scattered or dispersed light is weakened more than thelight passing perpendicularly through the layers because of its longer path, so that it is possible to produce in this way an additional improvement in the sharpness.

The above absorbing dyes must now meet a number of requirements.

The increase of definition that can beobtained with these .absorbing dyestutfs is inevitably associated with a reduction in the photographic sensitivity. Dyestulfs which still further reduce the sensitivity of the emulsion layers by virtue of their desensitizing properties are, of course, unsuitable.

The absorbing dyes, particularly when used for color photography, must be practically completely decolorized or removed subsequently because even a faint stain of residual dyestui can considerably impair the quality of a color image. Many dyestutfs which are decolorized by the agents used in the processing baths, e.g., by sodium sulte or potassium ferricyanide are useless because the decolorization is incomplete. It is therefore advantageous to use dyestuis which can be washed out of gelatin layers.

3,409,433 Patented Nov. 5, 1968 In order to prevent an unwanted coloring of the processmg baths which might deleiteri-ously affect the processing of the color photographic material, it is desirable to produce the required improvement in the sharpness of the image with the smallest possible quantities of dyestul additives.

The absorbing dyes are most effective when their absorption maxima coincide with or only differ very slightly from the sensitization maxima of the emulsion layer for whlch the dye is to be used. This effect is most ditlicult to obtain with green senstive layers since the sensitivity range of such layers of multilayer printing materials for color photography is narrower than that of other exposure materials. The highest lgreen sensitivity is usually 1n the range from 540- to 555 millmicrons and decreases sharply towards either side ofthis range, especially towards longer wavelengths.

Moreover, an absorbing dye intended for use in a green sensitive layer of multilayer photographic material with an interchanged layer arrangement as referred to hereinbefore, must not absorb in the blue region of the spectrum since such an absorption would cause an undesirable reduction in the light transmitted to the blue sensiive layer which is arranged below the green-sensitive ayer.

Absorbing dyes recommended for use in green-sensitive layers of color photographic materials are already known. These dyes, however, in particular the dyes described in German Patent No. 1,103,135 are of limited utility since they do not meet the requirements with respect to the absorption properties as described above.

It s among the objects of the present invention to provide absorbing dyes which are to be used in the greensensitive layers of multilayer color photographic materials having an interchanged layer arrangement, which are easily removable in the processing baths and the absorption maximum of which coincide with the sensitization range of the green-sensitive layer and which absorb light in the blue region of the spectrum in an amount as low as possible.

Other objects and advantages will become apparent from a consideration of the following description and examples.

We now have found that monoazo dyestuis of the following formula are excellently suitable for use as absorbing dyes for the green-sensitive layer of multilayer color-photographic materials:

sosM Mos- -SOaM In this formula R1 represents an alkoxy group, having preferably up to 5 carbon atoms, more especially a methoxy or an ethoxy group;

R2 represents a hydrogen atom or an alkoxy group as defined under R1;

R3 represents an acyl group, preferably an :acyl group originating (I) from a carboxylic acid, more preferably from an aliphatic carboxylic acid having up to 5 carbon atoms such as acetyl, propionyl, butyryl, valeryl, or the like, or (II) an organic sulfonic acid more preferably derived from a'phenyl sulphonic acid such as a toluene sulfonyl group or a benzene sulfonyl group;

M stands for any cation such as a hydrogen ion or generally a cation which forms a water-soluble salt, more especially a cation of an alkali metal such as sodium or potassium or an ammonium ion.

The dyes according to the invention can be completely (I) NH.CO.CH3

, I orroQ-rhN- l SONa NaOaS- -SOaa Absorption range, 490-585 my, Dico; Dmx.=0.22.

pH NrLcocrn l Culto-@Axims soma Naoisk/ -soaNa Absorption range, 490-S5 um, D400; Dmnx.=0.22.

Absorption range, 490-535 um, Diso; Dmnx.'=0.22.

CCH; OH NHCOCHs l l l CH3 NaOaS- -SOsNa .Absorption range, 490-585 mg, D400; Duma-:0.22.

In the annexed drawings, FIGURE 1 shows the absorption curves of the above dyestuifs II, III and IV (the line of crosses represents a third curve that is not drawn); and FIGURE 2 illustrates the sensitivity spectrum of the green-sensitive layer, before (left portion of curve) and after (right portion of curve) it is sensitized with a sensitizing dye of the following formula:

The dyes of the present invention are added in aqueous solution, advantageously in quantities of 1 to 6 g. per 100 g, of silver, to the green-sensitive silver halide emulsion before it is cast. Because of the high water solubility and the low affinity of the dyes for gelatin, it may be advantageous for the other emulsions, in addition to the green-sensitive layer, to be colored in the same way before casting.

The photographic silver halide emulsions in which the absorbing dyes are to be used can be optically sensitized. The usual optical sensitizing dyes for the green range of the Avisible spectrums can be used, such as cyanines, merocyanines, styryl dyes and the like.

The absorbing dyes can be used for silver chloride or bromide emulsions which may contain a small amount of up to mol percent of silver iodide or for emulsions containing silver chloride and silver bromide. While our invention is particularly directed to the ordinary silver halide gelatin emulsions, binding agents other than gelatin, e.g., polyvinyl alcohol or cellulose materials such as hydrolyzed cellulose acetate, carboxymethyl cellulose or.

the like which have no deleterious effect upon the lightsensitive materials, can be substituted for or combined with the gelatin.

The emulsions prepared in accordance with our invention can be coated in the usual manner upon any suitable support of, e.g., a cellulose ester such as cellulose acetate, polycarbonate especially of bis-hydroxyphenyl alkanes, polystyrene, a polyester in particular polyethylene terephthalate, etc.

The silver halide emulsions according to the invention can also containfsuch additives as chemical sensitizers, e.g., sulfo-sensitizers, various gold compounds, palladium compounds and the like. The emulsions can also be stabilized with mercury compounds such as described in U.S. Patents Nos. 2,728,663` and 2,728,665, triazoles, and azaindenes such as disclosed by Birr in Z. Wiss. Phot, vol. 47, 1952, pp. 2 to 28.

IThe emulsions may be hardened with any suitable harderier for the binding agent, for example, formaldehyde or derivatives of formaldehyde, cyclic 1,2-diketones and the like can be used for hardening gelatin.

The emulsions may further contain a coating aid such as wetting agents, for example, saponine, lauryl or oleyl monoether of polyethylene glycol, esters of glycerol and the like.

The kind of the magenta coupler used in the emulsion of the invention is not especially critical and is selected according to the requirements of the particular reproduction process in which the emulsion is to be used. Suitable are the common types of magenta coupler such as those of the pyrazolone series as described by O. Wahl yin Angewandte Chemie, volume 64, 1952, pages 259 to 265, as well as magenta couplers of thecyanine acetyl type, indazolones, or pyrazolobenzimidazoles, such as disclosed in British Patent No. 918,128 or U.S. Patent No. 3,061,- 432.

Example 1 ontneemt-@ Q o (ninemsn- This emulsion also contains the usual quantities of a stabilizer such as 250 mg. of 5-methyl7hydroxy2,3,4- triazaindolizine, a hardening agent as, for example, disclosed in German Patent No 872,153 and a wetting agent such as saponine (30 ml. of a 7.5 aqueous solution of saponine per kg. of emulsion are added);

(b) A gelatino-silver chlorobromide emulsion containing about 4 mol percent of silver bromide which is sensitized for the red part of the spectrum and which contains, per kg. of emulsion, 15 g. of the cyan coupler 1- hydroxy-Z-naphthoyl4sulphooctadecylamide, and 85 mi. of a 1% aqueous solution of the dyestuff according to Formula II, as well as a stabilizer such as 1-(psulfophenyl-amino)-2-methyl-5-mercapto-1,3,4,triazole in the form of 25 ml. of a 0.1% aqueous solution, a hardening agent and a wetting agent, for example, as mentioned under layer (a);

(c) A gelatino-silver chlorobromide emulsion as referred to under (b) which is sensitized to light ofthe green range of the spectrum and -which contains, per kg. of raw and 85 `ml. of the 1% `aqueous's'lolll'tiOpIl0f lthe screening dy'e'stuif according to'For'm'ula II, as wellasthe vstabilizing, hardening. and wetting agents, for example, those `usedin emu1siof1 (b) of this' example. jl

The multi-layer materialthus prepared fand dried contains 155 mg. of absorbing dye'. per square meterAymicro'- line screen was exposed on samples of this photographic material and also on those of'a 'standard material of the same type which is prepared f orl comparison purposes and which differs only from the above material in that it does not contain any absorbing dye. These samples were processed for.. 8 minutesin a color-forming developer of the following composition:V i i After subsequent bleaching, fixing and rinsing, according to common practice, the following fogging densities, measured at the unexposed areas, were obtained:

Cyan Magenta Yellow Standard 0. 09 0. 09 0. 10 Material with absorbing dye II- 0, 09 0. 10 0. 10

In the projection and with the microscopic evaluation of the screen exposures, a resolution of 140 lines/ mm. was obtained for the standard material and a resolution of 170 lines/mm. for the material which contained dye II, together with a considerably improved contrast reproduction.

In order to show that the absorbing dyes of the present invention do not deleteriously aifect the photographic material if present in the developing bath even in high concentrations the two materials described above were processed in a color-forming developer :bath of the above composition, to which had been added per litre the quantity of absorbing dye contained in 1 square meter of the photographic material. The following fogging values were obtained:

Cyan Magenta Yellow Standard 0. 09 0. 09 0. 11 Material with absorbing dye II- 0.09 0. 10 0` l1 The gradation and sensitivity values were practically unchanged.

Example 2 the usual quantities of stabilizing,` hardening and wetting agents'for example those described/'in Example 1, additionally containing per kg. of emulsion 6'0 ml. f'a 1% aqueous solution of the absorbing dye of Formula III; (b) A silver chlorobromide emulsion 'containing about 4 mol percent of silver bromidewhich is sensitized for light of the red region of the spectrum-and to which are added, per kg. of emulsion,l 15' g. of the cyan coupler according to Example 1, as well as the stabilizing, hardening-and wetting agentssuch as describ'ednin Example'l, and 6 (;)'ml.,v of a 1% aqueous. solution of the screening ,dyestuif according/to Formula III; (c)A A gelatino-silver,chlorobromide emulsion as describedhereinbefore under (b) which is sensitized lfor lightv of the green regionof the spectrumand tojwhich are added, per kg. .of emulsion, 13- g, of a magenta lcoupler having the following formula:

and'as well as the usual quantities of stabilizing hardening and weting agents such as described in Example l, and 6() ml. of Ythe 1% aqueous solution of the screening dyestuff according to Formula III.

The emulsions (a), (b) 4and (c) are coated in the above sequence onto a sheet-like support consisting of 'cellulose triacetate'. The dried multilayer material, which may comprise also the usual protective layers, contains :about mg. of absorbing dye according to Formula III per square meter.

A standard sample is prepared by using the same emulsions and additives, Ibut without the absorbing dyestuif. Microline screens are exposed onto samples of both materials, as in Example 1.

After identically, developing, rinsing, bleaching and fixing bot-h materials, the following fogging densities were measured at the unexposed areas:

Cyan Magenta Yellow Standard 0. 11 0. 10 0. 10 Material with absorbing dye III. 0. 10 0.09 0. 10

The evaluation of the screen exposures showed a resolution of lines per mm. for the material without dyestuif, and a resolution of lines per mm. for the material with absorbing dyestuff, with considerably improved contrast reproduction.

Example 3 For the formation of a three-layer positive film, the emulsions (a), (b) and (c) are prepared as described in Example 2, but (a) and (b) do not contain any absorbing dyestuff and (c) contains, per kg. of emulsion, 200 ml. of the 1% aqueous solution of thev :absorbing dye according to Formula III.

Samples of this multilayer material are exposed and processed in the same manner as in the previous exam- `ples. `Compared with the samples of the material. referred v, sOiM.A

wherein' R1 standsv for an alkoxy group having up toi5 carbon atoms; R2 is amemberof'the group-consisting of hydrogen and `an alkoxy group 'havinglu'pfto 5 carbon atoms; and R3 stnads for an a'c'yl group and M represents acation, the dye being in'readily/ rinsed-outcondition so that it is removed during processing `but :increasesthe r resolving power and contrast of the image. 'ia t t 2. A photographic silver halide emulsion as defined in claim 1, wherein R3 is an acyl group of an aliphatic carboxylic acid with 1.-5 carbon atoms.

3. A photographic silver halide emulsion as defined in claim 1, wherein R3 is a phenyl sulfonyl group.

4. In a photographic multilayer element comprising a sheet-like support having coated thereon the following silver halide emulsion layers:

(a) closest to the support a layer sensitive to the blue region of the spectrum :and which contains a color coupler that forms a yellow image upon color development;

(b) further from t'he support a layer sensitive to the red region of the spectrum and which contains a color coupler that forms a cyan image upon color development; and v (c) also further from the support a layer sensitive to the green region of the spectrum and which contains a color coupler that forms a magenta image upon color development, the improvement according Y tofwhich Aatleastl the green-'sensitive layer `(c) con- "tains in an amount-of 055 to 10g. per mol of silver halide of a water-soluble dye of the following forwherein R1 stands for an alkoxy group having up to 5 carbon atoms; R3 is a member of the groupv consisting of hydrogen and an alkoxy group having up to 5 carbon atoms; and R3 stands for an acyl group and M represents a cation, the dye being in readily rinsedmout condition so that it is removed during processing ,bu'tincreases'th'e resolving power and con- ;-itf-ast @fue image-1' L i 5.' AL'photofgraiphicv multilayer lernent lasden'ed in claim 4, wherein R3`is anv acyl group of an aliphatic carboxylic ac idwith'l-S carbon atoms. l (f6. A photographic' multilayer element is defined in claim 4, wherein R3 is a phenyl `sulfonyl group.

'References Cited r NORMAN G. TORCHIN, Primary Examiner.

R. H. SMITH, Assistant Examiner. 

